| 1. |
- Andres, Blanca, et al.
(author)
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Response of stone wool–insulated building barriers under severe heating exposures
- 2018
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In: Journal of Fire Sciences. - : SAGE Publications. - 0734-9041 .- 1530-8049. ; 36:4, s. 315-341
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Journal article (peer-reviewed)abstract
- This article presents the experimental results of stone wool–layered sandwich constructions, with either steel or gypsum claddings, tested under four different heating exposures: 7 kW/m2 incident radiant heat flux exposure, 60 kW/m2 incident radiant heat flux exposure, parametric time–temperature curve exposure and ISO 834 standard time–temperature exposure. The test apparatus used were a movable radiant panel system, a mid-scale furnace (1.5 m3) and a large-scale furnace (15 m3). The results show that reduced-scale tests are capable of reproducing the heat transferred through the construction at large scale provided there is limited mechanical degradation. The results indicate that the availability of oxygen is fundamental to the fire behaviour of the sandwich composites tested. Reactions occurring in stone wool micro-scale testing, such as oxidative combustion of the binder or crystallisation of the fibres, have a limited effect on the temperature increase when wool is protected from air entrainment.
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| 2. |
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| 3. |
- Bhargava, Abhishek
(author)
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Fire behaviour of selected polymeric materials : Numerical modelling and validation using microscale and bench scale test methods
- 2020
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Doctoral thesis (other academic/artistic)abstract
- The ability to predict fire behaviour of materials is of key interest to building materials industry. Themain reason for it is expensive fire testing and certification costs borne by the manufacturers to bring a finished product to market. Failure in a fire test leads to increased expenses in the productdevelopment cycle leading to delayed realization of profits and low cost competitiveness in themarket. Numerical modelling and fire simulations is a less expensive method to predict the outcomesof a real fire test. However, the state of the art models existing in literature suffer from severalshortcomings. A few of them are related to inadequacies related to material property data used inthem as input values. Others include modelling deficiencies pertaining to accurate description ofphysicochemical processes involved in materials during the fire. Often hurdles in implementation ofappropriate numerical methods are also a cause of poor predictability of mathematical models. In this industrial PhD work, a novel one-dimensional computational pyrolysis model was developed using a combination of deterministic and stochastic approach. The tool is capable of prediction of key fire technical properties of interest obtained in a standard cone calorimeter device such as mass loss rate (MLR), heat release rate (HRR), total heat released (THR). The developed model could beincorporated into a bigger CFD code and can be used for estimation of fire growth rate onsuccessively bigger material scale. The performance of novel pyrolysis model considers severalphysicochemical transformation complexities occurring in the material and renders a satisfactoryperformance of the investigated materials on microscale and bench scale level simulations.
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| 4. |
- Bhargava, Abhishek, et al.
(author)
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Performance analysis of a heat transfer and sub-grid chemical reaction distributed activation energy model for fire simulations
- 2019
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In: Journal of Fire Sciences. - : SAGE Publications. - 0734-9041 .- 1530-8049. ; 37:1, s. 18-46
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Journal article (peer-reviewed)abstract
- A heat transfer and sub-grid chemical reaction kinetic model for solid phase combustion of a charring polymer is presented based on distributed reactivity modeling approach. The model is used to compute flammability parameters of a polymer sheet of a given thickness to simulate test results of a cone calorimeter experiment. Comparison of model simulations with cone calorimeter test data shows that it gives reasonable prediction of mass loss rate, heat release rate, and total heat released of poly-vinyl chloride (PVC) and ethyl vinyl acetate–aluminum tri-hydroxide (EVA-ATH). The solution of governing equations with the current form of distributed reactivity modeling model poses numerical challenges due to appearance of a double integral in the chemical reaction model. Hence, an analytical approximation has been derived to solve mass and energy conservation equations representing the model. Simulation results indicate that with the approximated form of the distributed reactivity modeling model, along with the input parameters retrieved from literature, the model shows comparatively good predictions for EVA-ATH for mass loss rate, heat release rate, and total heat released, but calculates under-predicted values for PVC.
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| 5. |
- Bhargava, Abhishek, et al.
(author)
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Pyrolysis modeling of PVC and PMMA using a distributed reactivity model
- 2016
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In: Polymer Degradation and Stability. - : Elsevier BV. - 0141-3910. ; 129, s. 199-211
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Journal article (peer-reviewed)abstract
- The thermal decomposition kinetics of poly(vinyl chloride) (PVC) and poly(methyl methacrylate) (PMMA) was studied by thermogravimetry using non isothermal experiments. A detailed kinetic analysis was done using the isoconversional methods (model-free) (including Friedman, Kissinger-Akhaira-Sunose (KAS) and Kissinger methods) and distributed reactivity model (model-fitting). The overall aim was to retrieve kinetic parameters of the model describing the differential thermogravimetric (DTG) curve. For distributed reactivity models, both double and multi-Gaussian methods were used to explain the thermal decomposition process in these polymers. Apparent kinetic parameters were retrieved using optimization calculations with a newly developed computer code using MATLAB® involving pattern search algorithm. Modeling results were compared with the experimental data obtained in a simultaneous thermal analyzer (STA). Agreement between experimental tests and simulations showed good results for fire modeling applications for these polymers.
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| 6. |
- Bhargava, Abhishek, et al.
(author)
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Pyrolysis modeling of pvcusing distributed activation energy model-micro scale testing
- 2017
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In: Proceedings of the International Conference on Applications of Structural Fire Engineering, ASFE 2015. - : Czech Technical University in Prague - Central Library. - 2336-7318. - 9788001061947
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Conference paper (peer-reviewed)abstract
- Polyvinyl chloride (PVC) is a common thermoplastic whichfinds widespread applications in the construction industry for usage inceiling linings, flooring materials, electrical cables and roofing materials. Several fire requirements are put on these types of applications. For fire safety engineering and product development, thermo-chemical decomposition modeling of PVC isrequired. The FIRETOOLS project investigates the possibilities to predict real scale fire behavior of building products, content and barriers by means of using material data on successively increasing scale. This paper focuses on the material modeling and studiesthe thermo-chemical decomposition of PVC using Distributed Activation Energy Model (DAEM).
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| 7. |
- Livkiss, Karlis, et al.
(author)
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Characterization of stone wool properties for fire safety engineering calculations
- 2018
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In: Journal of Fire Sciences. - : SAGE Publications. - 0734-9041 .- 1530-8049. ; 36:3, s. 202-223
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Journal article (peer-reviewed)abstract
- Prediction of the insulating capability of building products in fire conditions would support the product development process. Stone wool insulation is a widely used material in fire barrier constructions. Due to the combustion of its organic content, the temperature inside stone wool can rise above the temperature of the exposed boundary. This temperature rise is difficult to predict. An extensive test program was performed to obtain the thermal and reaction kinetic properties of stone wool. The test methods included modified slug calorimeter, thermogravimetric analysis, differential scanning calorimetry, micro-scale combustion calorimetry and bomb calorimetry. The thermal conductivity in elevated temperatures was similar for all the investigated products. Two positive mass loss rate and heat release rate peaks were observed in temperatures between 20°C and 700°C. Reaction kinetic parameters were obtained and used in a finite difference model predicting the temperature increase in stone wool upon linear heating.
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| 8. |
- Van Hees, Patrick, et al.
(author)
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Analysis of fire barriers with respect to fires with combustible gases and liquids
- 2017
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In: 15th International Conference and Exhibition on Fire and Materials 2017. - 9781510846746 ; 1, s. 146-157
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Conference paper (peer-reviewed)abstract
- Fires including flammable gases and/or liquids differ from typical residential fires where the fuel is mainly composed of solid combustibles. The traditional ISO 834 curve was established to represent the timetemperature curve for a fully developed fire. However for combustible gases the type of thermal exposure might be substantially different and therefore other curves have been developed such as the hydrocarbon curve (HCC) and the jetfire exposure. Knowledge on how test results from traditional ISO 834 fire test can be used to estimate the behaviour under HCC or jetfire conditions is limited. The Swedish Contingency Agency MSB initiated research on this topic to find correlation or guidance rules. For this reason, both literature studies, statistical studies, calculation and fire tests were performed. Fire tests were performed at different scales and levels, and this paper focuses mainly on a real scale fire test conducted in a 2-container set-up where one of the containers doors was replaced by a typical fire barrier. It was observed that the exposure in a real fire is different with respect to pressure, temperature levels and temperature distributions. While the real fire test had a long period of lower room temperatures before it fully developed, the unequal temperature distribution as well as the radiative heat transfer from the pool fire resulted in a fire resistance, which was close to the rating of the wall according to ISO 834. Taking into account the results of the other fire test as well as calculations, it could be concluded that heat exposure from hydrocarbon fires will lead to a substantial decrease of fire rating. On top of this it was observed that certain materials do not resist sufficiently to, for example a jet fire exposure. Hence it is important to perform a full risk analysis when choosing an appropriate fire barrier for fires, which can include combustible gases and liquids.
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